Various forms of control valves by which the operator of an air braked vehicle can control the interconnection between an air reservoir and a spring applied parking brake are known in the art. For example, see U.S. Pat. No. 3,519,312 (O. B. Cruse) entitled CONTROL VALVE and issued on July 7, 1972 to the assignee of the present invention, the disclosure of which is incorporated herein by reference. Another example of such a control valve is described in U.S. Pat. No. 3,746,401 (G. W. Stearns) entitled CONTROL VALVE AND SYSTEM and issued on July 17, 1973 to the assignee of the present invention, the disclosure of which is also incorporated herein by reference.
None of the known control valves of this type have any kind of antitheft feature, i.e., means by which a would-be thief is prevented from operating the control valve so as to release the brakes and thereafter drive off with the vehicle.